﻿using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;

namespace Daramkun.Liqueur.IO.Compression.Utilities
{
	internal class SharedUtils
	{
		public static int URShift ( int number, int bits )
		{
			return ( int ) ( ( uint ) number >> bits );
		}

		public static int ReadInput ( TextReader sourceTextReader, byte [] target, int start, int count )
		{
			if ( target.Length == 0 ) return 0;

			char [] charArray = new char [ target.Length ];
			int bytesRead = sourceTextReader.Read ( charArray, start, count );

			if ( bytesRead == 0 ) return -1;

			for ( int index = start; index < start + bytesRead; index++ )
				target [ index ] = ( byte ) charArray [ index ];

			return bytesRead;
		}

		internal static byte [] ToByteArray ( string sourceString )
		{
			return System.Text.UTF8Encoding.UTF8.GetBytes ( sourceString );
		}

		internal static char [] ToCharArray ( byte [] byteArray )
		{
			return System.Text.UTF8Encoding.UTF8.GetChars ( byteArray );
		}
	}

	internal sealed class StaticTree
	{
		internal static readonly short [] lengthAndLiteralsTreeCodes = new short [] {
            12, 8, 140, 8, 76, 8, 204, 8, 44, 8, 172, 8, 108, 8, 236, 8,
            28, 8, 156, 8, 92, 8, 220, 8, 60, 8, 188, 8, 124, 8, 252, 8,
             2, 8, 130, 8, 66, 8, 194, 8, 34, 8, 162, 8, 98, 8, 226, 8,
            18, 8, 146, 8, 82, 8, 210, 8, 50, 8, 178, 8, 114, 8, 242, 8,
            10, 8, 138, 8, 74, 8, 202, 8, 42, 8, 170, 8, 106, 8, 234, 8,
            26, 8, 154, 8, 90, 8, 218, 8, 58, 8, 186, 8, 122, 8, 250, 8,
             6, 8, 134, 8, 70, 8, 198, 8, 38, 8, 166, 8, 102, 8, 230, 8,
            22, 8, 150, 8, 86, 8, 214, 8, 54, 8, 182, 8, 118, 8, 246, 8,
            14, 8, 142, 8, 78, 8, 206, 8, 46, 8, 174, 8, 110, 8, 238, 8,
            30, 8, 158, 8, 94, 8, 222, 8, 62, 8, 190, 8, 126, 8, 254, 8,
             1, 8, 129, 8, 65, 8, 193, 8, 33, 8, 161, 8, 97, 8, 225, 8,
            17, 8, 145, 8, 81, 8, 209, 8, 49, 8, 177, 8, 113, 8, 241, 8,
             9, 8, 137, 8, 73, 8, 201, 8, 41, 8, 169, 8, 105, 8, 233, 8,
            25, 8, 153, 8, 89, 8, 217, 8, 57, 8, 185, 8, 121, 8, 249, 8,
             5, 8, 133, 8, 69, 8, 197, 8, 37, 8, 165, 8, 101, 8, 229, 8,
            21, 8, 149, 8, 85, 8, 213, 8, 53, 8, 181, 8, 117, 8, 245, 8,
            13, 8, 141, 8, 77, 8, 205, 8, 45, 8, 173, 8, 109, 8, 237, 8,
            29, 8, 157, 8, 93, 8, 221, 8, 61, 8, 189, 8, 125, 8, 253, 8,
            19, 9, 275, 9, 147, 9, 403, 9, 83, 9, 339, 9, 211, 9, 467, 9,
            51, 9, 307, 9, 179, 9, 435, 9, 115, 9, 371, 9, 243, 9, 499, 9,
            11, 9, 267, 9, 139, 9, 395, 9, 75, 9, 331, 9, 203, 9, 459, 9,
            43, 9, 299, 9, 171, 9, 427, 9, 107, 9, 363, 9, 235, 9, 491, 9,
            27, 9, 283, 9, 155, 9, 411, 9, 91, 9, 347, 9, 219, 9, 475, 9,
            59, 9, 315, 9, 187, 9, 443, 9, 123, 9, 379, 9, 251, 9, 507, 9,
             7, 9, 263, 9, 135, 9, 391, 9, 71, 9, 327, 9, 199, 9, 455, 9,
            39, 9, 295, 9, 167, 9, 423, 9, 103, 9, 359, 9, 231, 9, 487, 9,
            23, 9, 279, 9, 151, 9, 407, 9, 87, 9, 343, 9, 215, 9, 471, 9,
            55, 9, 311, 9, 183, 9, 439, 9, 119, 9, 375, 9, 247, 9, 503, 9,
            15, 9, 271, 9, 143, 9, 399, 9, 79, 9, 335, 9, 207, 9, 463, 9,
            47, 9, 303, 9, 175, 9, 431, 9, 111, 9, 367, 9, 239, 9, 495, 9,
            31, 9, 287, 9, 159, 9, 415, 9, 95, 9, 351, 9, 223, 9, 479, 9,
            63, 9, 319, 9, 191, 9, 447, 9, 127, 9, 383, 9, 255, 9, 511, 9,
             0, 7, 64, 7, 32, 7, 96, 7, 16, 7, 80, 7, 48, 7, 112, 7,
             8, 7, 72, 7, 40, 7, 104, 7, 24, 7, 88, 7, 56, 7, 120, 7,
             4, 7, 68, 7, 36, 7, 100, 7, 20, 7, 84, 7, 52, 7, 116, 7,
             3, 8, 131, 8, 67, 8, 195, 8, 35, 8, 163, 8, 99, 8, 227, 8
        };

		internal static readonly short [] distTreeCodes = new short [] {
            0, 5, 16, 5, 8, 5, 24, 5, 4, 5, 20, 5, 12, 5, 28, 5,
            2, 5, 18, 5, 10, 5, 26, 5, 6, 5, 22, 5, 14, 5, 30, 5,
            1, 5, 17, 5, 9, 5, 25, 5, 5, 5, 21, 5, 13, 5, 29, 5,
            3, 5, 19, 5, 11, 5, 27, 5, 7, 5, 23, 5 };

		internal static readonly StaticTree Literals;
		internal static readonly StaticTree Distances;
		internal static readonly StaticTree BitLengths;

		internal short [] treeCodes;
		internal int [] extraBits;
		internal int extraBase;
		internal int elems;
		internal int maxLength;

		static StaticTree ()
		{
			Literals = new StaticTree ( lengthAndLiteralsTreeCodes, Tree.ExtraLengthBits, ZlibConstants.LITERALS + 1, ZlibConstants.L_CODES, ZlibConstants.MAX_BITS );
			Distances = new StaticTree ( distTreeCodes, Tree.ExtraDistanceBits, 0, ZlibConstants.D_CODES, ZlibConstants.MAX_BITS );
			BitLengths = new StaticTree ( null, Tree.extra_blbits, 0, ZlibConstants.BL_CODES, ZlibConstants.MAX_BL_BITS );
		}

		private StaticTree ( short [] treeCodes, int [] extraBits, int extraBase, int elems, int maxLength )
		{
			this.treeCodes = treeCodes;
			this.extraBits = extraBits;
			this.extraBase = extraBase;
			this.elems = elems;
			this.maxLength = maxLength;
		}
	}

	static class Adler
	{
		private static readonly uint BASE = 65521;
		private static readonly int NMAX = 5552;

		public static uint Adler32 ( uint adler, byte [] buf, int index, int len )
		{
			if ( buf == null )
				return 1;

			uint s1 = ( uint ) ( adler & 0xffff );
			uint s2 = ( uint ) ( ( adler >> 16 ) & 0xffff );

			while ( len > 0 )
			{
				int k = len < NMAX ? len : NMAX;
				len -= k;
				while ( k >= 16 )
				{
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					s1 += buf [ index++ ]; s2 += s1;
					k -= 16;
				}
				if ( k != 0 )
				{
					do
					{
						s1 += buf [ index++ ];
						s2 += s1;
					}
					while ( --k != 0 );
				}
				s1 %= BASE;
				s2 %= BASE;
			}
			return ( uint ) ( ( s2 << 16 ) | s1 );
		}
	}
}
